Quantum Physics - Mass of Data

[Jaybird180]

Let's say you buy a new Hard Drive, something in the multiple terabyte range...multiple Petabyte range, in-fact. You unwrap the package on put it on the world's most accurate scale. It measures accurately down to the yoctogram (10^-24 grams).

You format the new disk and begin filling it with your data. After the drive is full, you weigh it again.

Does the drive's mass have a delta? Yes or No?

Does your answer change if the drive is a solid-state vs mechanical drive? Which drive has the larger delta?


----Edit------
Please explain your answers

 

[Jim Logajan]

Assuming the hard drive is allowed to come to thermal equilibrium with its surroundings before being weighed, and it isn't in an external magnetic field, I don't see why there would be any change in energy or mass. The energy in the different orientations of the magnetic domains should not cause any net change in energy. I suspect if you impose an external magnetic field and store all "1" bits and compare the weight to the same drive that has all the bits "0" then I think you should find a difference in weight.

There is a definite change in entropy, though, regardless of technology used.

EDIT: I meant information entropy.

 

[Jim Logajan]

In fact, here's a demo that will help both of you see why it has no impact on entropy or weight:

10110101111010101101010
01111000111111110110100

Which one of those would weigh more? Ok, is it possible to put it back to the original point (aka, negating entropy?)
10110101111010101101010

Yep.

Well if you use different font weights, and a "1" weighs less than a "0" .....

 

[Jim Logajan]

Okay - to get topic back on track:

The electrical charge applied to the sectors, platters of the drive are electrons, which turn an off state to an on state (0 to 1). Electrons have mass. Therefore the mass of the drive has increased.

All the hard drives I'm familiar with store information by changing orientation of magnetic domains. There is no change in the number of electrons - if there were the drive would not stay electrically neutral.

 

[Jim Logajan]

No.

You have a static weight, because the same effort turning a 1 to a 0 is also turning a 0 to a 1. There's no net gain or loss of any electrons, neutrons, protons, weight, or anything else.

It takes energy to turn those domains, so the platter heats up. That heat has mass. However, that mass change is a consequence of the writing process, not the information content.

There is a allegedly a lower limit on the amount of energy that has to be expended in switching bits. See http://en.wikipedia.org/wiki/Landauer's_principle

Think of it in laymans terms: You have a switch on a wall - does it weigh more to have the switch be up, or down?

Ahem. The switch in the up position has slightly more potential energy than when it is in the down position....

Better make that a switch that toggles left and right.

 

[Jim Logajan]

????????????????

I freely admit my knowledge of physics is limited to Science Channel and reading science magazines since I was a kid.
Please educate me.

You might find this more educational and possibly more authoritative than from "some guy on the internet":
http://plato.stanford.edu/entries/equivME/#1.2.1

Weight = Mass * Gravity. What does potential energy have to do with it?

If E=mc[sup]2[/sup], then m=E/c[sup]2[/sup]. Shouldn't matter what form the energy E takes. However, you do have a point because the potential energy isn't in the switch itself but is probably in the gravitational field between the earth and the switch. At least I think that is the case.